The present invention relates generally to workpiece securing apparatuses and more specifically to a powered clamp with an unlocking feature.
Pneumatically powered clamps have been used to secure workpieces, such as sheet metal panels for automotive vehicles, during welding, gauging or other industrial manufacturing operations. One such device is disclosed in U.S. Pat. No. 5,884,903 entitled xe2x80x9cPowered Clamp and Gauging Apparatusxe2x80x9d which issued to the present inventor on Mar. 23, 1999. This patent is incorporated by reference herein.
On occasion, there is a need to manually assist retracting movement of the piston rod, slide, link, hub and arm. One conventional resetting device is shown in U.S. Pat. No. 5,845,897 entitled xe2x80x9cToggle Lever Clamp Device for Automobile Body Fabricationxe2x80x9d which issued to Tunkers on Dec. 8, 1998. In another clamp, a non-rotating, linearly moving and unthreaded, spool-type reset button has been employed to manually retract a slide and to serve as a supplemental stop. These resetting devices, however, project from an end of the clamp and are prone to undesired contact with passing workpieces or other machinery. Furthermore, these traditional, linearly moving resetting devices also serve as stops for the slide. Notwithstanding, manufacturing plant contamination settling on the greased spool or threads may inadvertently alter the stop location relative to the clamp housing after continuous use.
In accordance with the present invention, a workpiece securing apparatus or clamp includes a piston, a coupling or transmission mechanism, and an unlock device. In another aspect of the present invention, the unlock device is rotatable to move the coupling mechanism. Still another aspect of the present invention provides a mechanism which converts linear movement of a piston to rotary motion of a hub and workpiece interfacing arm. In yet another aspect of the present invention, a rotational axis of the unlock device is generally parallel to a rotational axis of the arm
The clamp securing apparatus of the present invention is advantageous over traditional devices in that the present invention does not elongate the overall length of the apparatus. Furthermore, the unlock device does not project outside of the nominal width of the apparatus for one form of the invention. Moreover, the unlock device of the present invention is more reliably sealed to the adjacent housing as compared to conventional devices, thereby minimizing containment intrusion. Additionally, the tolerances and positioning of the unlock device do not impact the stopping location of the mechanism and arm, in another form of the invention. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.